LIPID CHANGES IN BELL PEPPER FRUIT DURING CHILLING AND REWARMING

Abstract

Lipid composition and pigment content in bell pepper fruit that were freshly harvested, chilled 2 weeks at 2C (CH), or chilled then rewarmed to 20C for 4 days (RW), were determined. There was slight to moderate loss of glycerolipids during chilling, with much greater losses after rewarming. Loss of galactolipid (GL) exceeded that of phospholipid (PL). The ratio of the GL, MGDG:DGDG, did not change in CH and RW fruit, and there was no loss of chlorophyll or change in the Chl a:b ratio, but neutral carotenes declined ca 30 % after rewarming. Only small changes in total membrane sterols (TMS) were noted in CH and RW fruit, but major changes in sterol glycosylation and esterificatian occurred. The stigmasterol:sitosterol ratio increased during chilling and after rewarming. Due to PL loss, the ratios of TMS and cerebrosides to PL increased sharply in RW fruit. The ratio of 18:2 to 18:3 declined with chilling and with rewarming in all acyl lipids, but total unsaturation increased only in GL. These results indicate that most membrane damage occurs after rewarming and that the chloroplasts are especially chilling sensitive.